The present application relates to a method and device for positioning of a self-baking filler electrode in electrical reduction and arc furnaces, particularly under utilization of electrodes having a jacket with radially outwardly extending longitudinal ribs or fins provided for engagement with positioning structure.
Electrothermic smelting and melting furnaces particularly electrically operated reduction furnaces with or without arc type heating usually employ self baking filler electrodes of the so called Soederberg type. These filling electrodes are comprised of a thin, shaping sheet metal jacket filled with the consumable material. These electrodes are very sensitive against radial impacts, pressures or the like as they may occur; "radial" of course to be understood in relation to the axis of the electrode. Upon installing such electrodes they require usually a device for placing the electrode tip or end into a particular elevational position which is to be maintained and necessary or advantageous for metallurgical procedure. Repositioning the electrode is a continuous operation in order to offset the dimensional variations as the electrode is consumed.
German Pat. No. 83 14 30 discloses such an electrode feeding structure with a gear transmission of the rack and pinion drive variety. Projections, generally speaking, are movable parallel to the axis of the electrode and engage indents in the electrode jacket. The indents could actually be provided for during operation and synchronously with the feeding operation and by means of a structure which is separated from the electrode feeding device.
On holding as well as during feeding of the electrodes radial forces will therefore be exerted on the jacket. These are necessary in order to prevent uncontrolled slide through of the electrode. Controlling these forces and the radial forces for providing the indents is actually quite difficult. Swiss Pat. No. 323760 discloses a similar electrode feeding device of this type which requires a prefabricated groove in the electrode to receive a rack to be moved by a pinion.
German Pat. No. 33 04 099 discloses structure wherein a clamping device engages radially the jacket and here outwardly extending longitudinal ribs. This electrode drive device is disadvantaged by the fact that they are technically of rather complicated construction for moving the electrode one needs twice as many clamping structures. The duplication in number is required since only half of the clamping brackets will engage the ribs for a certain period of time and the have to be released and returned to re-engage the structure. During that period of course the electrode is not permitted to slide and that is the reason a second set of clamping brackets is needed.
In addition the clamping elements have to be pressure biased for emergency cases for example in case of an electric current failure, a pressure drop or the like; the electrodes must be held firmly and must not be permitted to move in an uncontrolled fashion. The emergency arrangement includes spring operated clamping brackets which means that higher release pressure is required for disengagement to overcome the spring bias.